diff options
| -rw-r--r-- | drivers/mtd/devices/Kconfig | 9 | ||||
| -rw-r--r-- | drivers/mtd/devices/docg3.c | 116 | ||||
| -rw-r--r-- | drivers/mtd/devices/docg3.h | 11 |
3 files changed, 113 insertions, 23 deletions
diff --git a/drivers/mtd/devices/Kconfig b/drivers/mtd/devices/Kconfig index 283d887..952e956 100644 --- a/drivers/mtd/devices/Kconfig +++ b/drivers/mtd/devices/Kconfig @@ -251,6 +251,8 @@ config MTD_DOC2001PLUS config MTD_DOCG3 tristate "M-Systems Disk-On-Chip G3" + select BCH + select BCH_CONST_PARAMS ---help--- This provides an MTD device driver for the M-Systems DiskOnChip G3 devices. @@ -259,6 +261,13 @@ config MTD_DOCG3 M-Systems and now Sandisk. The support is very experimental, and doesn't give access to any write operations. +if MTD_DOCG3 +config BCH_CONST_M + default 14 +config BCH_CONST_T + default 4 +endif + config MTD_DOCPROBE tristate select MTD_DOCECC diff --git a/drivers/mtd/devices/docg3.c b/drivers/mtd/devices/docg3.c index 1f949ea..26cc179 100644 --- a/drivers/mtd/devices/docg3.c +++ b/drivers/mtd/devices/docg3.c @@ -29,6 +29,9 @@ #include <linux/delay.h> #include <linux/mtd/mtd.h> #include <linux/mtd/partitions.h> +#include <linux/bitmap.h> +#include <linux/bitrev.h> +#include <linux/bch.h> #include <linux/debugfs.h> #include <linux/seq_file.h> @@ -42,7 +45,6 @@ * As no specification is available from M-Systems/Sandisk, this drivers lacks * several functions available on the chip, as : * - IPL write - * - ECC fixing (lack of BCH algorith understanding) * - powerdown / powerup * * The bus data width (8bits versus 16bits) is not handled (if_cfg flag), and @@ -51,8 +53,7 @@ * DocG3 relies on 2 ECC algorithms, which are handled in hardware : * - a 1 byte Hamming code stored in the OOB for each page * - a 7 bytes BCH code stored in the OOB for each page - * The BCH part is only used for check purpose, no correction is available as - * some information is missing. What is known is that : + * The BCH ECC is : * - BCH is in GF(2^14) * - BCH is over data of 520 bytes (512 page + 7 page_info bytes * + 1 hamming byte) @@ -75,6 +76,11 @@ static struct nand_ecclayout docg3_oobinfo = { .oobavail = 8, }; +/** + * struct docg3_bch - BCH engine + */ +static struct bch_control *docg3_bch; + static inline u8 doc_readb(struct docg3 *docg3, u16 reg) { u8 val = readb(docg3->base + reg); @@ -582,6 +588,54 @@ static void doc_hamming_ecc_init(struct docg3 *docg3, int nb_bytes) } /** + * doc_correct_data - Fix if need be read data from flash + * @docg3: the device + * @buf: the buffer of read data (512 + 7 + 1 bytes) + * @hwecc: the hardware calculated ECC. + * It's in fact recv_ecc ^ calc_ecc, where recv_ecc was read from OOB + * area data, and calc_ecc the ECC calculated by the hardware generator. + * + * Checks if the received data matches the ECC, and if an error is detected, + * tries to fix the bit flips (at most 4) in the buffer buf. As the docg3 + * understands the (data, ecc, syndroms) in an inverted order in comparison to + * the BCH library, the function reverses the order of bits (ie. bit7 and bit0, + * bit6 and bit 1, ...) for all ECC data. + * + * The hardware ecc unit produces oob_ecc ^ calc_ecc. The kernel's bch + * algorithm is used to decode this. However the hw operates on page + * data in a bit order that is the reverse of that of the bch alg, + * requiring that the bits be reversed on the result. Thanks to Ivan + * Djelic for his analysis. + * + * Returns number of fixed bits (0, 1, 2, 3, 4) or -EBADMSG if too many bit + * errors were detected and cannot be fixed. + */ +static int doc_ecc_bch_fix_data(struct docg3 *docg3, void *buf, u8 *hwecc) +{ + u8 ecc[DOC_ECC_BCH_SIZE]; + int errorpos[DOC_ECC_BCH_T], i, numerrs; + + for (i = 0; i < DOC_ECC_BCH_SIZE; i++) + ecc[i] = bitrev8(hwecc[i]); + numerrs = decode_bch(docg3_bch, NULL, DOC_ECC_BCH_COVERED_BYTES, + NULL, ecc, NULL, errorpos); + BUG_ON(numerrs == -EINVAL); + if (numerrs < 0) + goto out; + + for (i = 0; i < numerrs; i++) + errorpos[i] = (errorpos[i] & ~7) | (7 - (errorpos[i] & 7)); + for (i = 0; i < numerrs; i++) + if (errorpos[i] < DOC_ECC_BCH_COVERED_BYTES*8) + /* error is located in data, correct it */ + change_bit(errorpos[i], buf); +out: + doc_dbg("doc_ecc_bch_fix_data: flipped %d bits\n", numerrs); + return numerrs; +} + + +/** * doc_read_page_prepare - Prepares reading data from a flash page * @docg3: the device * @block0: the first plane block index on flash memory @@ -762,7 +816,7 @@ static int doc_read_oob(struct mtd_info *mtd, loff_t from, u8 *oobbuf = ops->oobbuf; u8 *buf = ops->datbuf; size_t len, ooblen, nbdata, nboob; - u8 calc_ecc[DOC_ECC_BCH_SIZE], eccconf1; + u8 hwecc[DOC_ECC_BCH_SIZE], eccconf1; if (buf) len = ops->len; @@ -797,7 +851,7 @@ static int doc_read_oob(struct mtd_info *mtd, loff_t from, ret = doc_read_page_prepare(docg3, block0, block1, page, ofs); if (ret < 0) goto err; - ret = doc_read_page_ecc_init(docg3, DOC_ECC_BCH_COVERED_BYTES); + ret = doc_read_page_ecc_init(docg3, DOC_ECC_BCH_TOTAL_BYTES); if (ret < 0) goto err_in_read; ret = doc_read_page_getbytes(docg3, nbdata, buf, 1); @@ -811,7 +865,7 @@ static int doc_read_oob(struct mtd_info *mtd, loff_t from, doc_read_page_getbytes(docg3, DOC_LAYOUT_OOB_SIZE - nboob, NULL, 0); - doc_get_hw_bch_syndroms(docg3, calc_ecc); + doc_get_hw_bch_syndroms(docg3, hwecc); eccconf1 = doc_register_readb(docg3, DOC_ECCCONF1); if (nboob >= DOC_LAYOUT_OOB_SIZE) { @@ -825,18 +879,28 @@ static int doc_read_oob(struct mtd_info *mtd, loff_t from, doc_dbg("OOB - UNUSED: %02x\n", oobbuf[15]); } doc_dbg("ECC checks: ECCConf1=%x\n", eccconf1); - doc_dbg("ECC CALC_ECC: %02x:%02x:%02x:%02x:%02x:%02x:%02x\n", - calc_ecc[0], calc_ecc[1], calc_ecc[2], - calc_ecc[3], calc_ecc[4], calc_ecc[5], - calc_ecc[6]); - - ret = -EBADMSG; - if (block0 >= DOC_LAYOUT_BLOCK_FIRST_DATA) { - if ((eccconf1 & DOC_ECCCONF1_BCH_SYNDROM_ERR) && - (eccconf1 & DOC_ECCCONF1_PAGE_IS_WRITTEN)) - goto err_in_read; - if (is_prot_seq_error(docg3)) - goto err_in_read; + doc_dbg("ECC HW_ECC: %02x:%02x:%02x:%02x:%02x:%02x:%02x\n", + hwecc[0], hwecc[1], hwecc[2], hwecc[3], hwecc[4], + hwecc[5], hwecc[6]); + + ret = -EIO; + if (is_prot_seq_error(docg3)) + goto err_in_read; + ret = 0; + if ((block0 >= DOC_LAYOUT_BLOCK_FIRST_DATA) && + (eccconf1 & DOC_ECCCONF1_BCH_SYNDROM_ERR) && + (eccconf1 & DOC_ECCCONF1_PAGE_IS_WRITTEN) && + (ops->mode != MTD_OPS_RAW) && + (nbdata == DOC_LAYOUT_PAGE_SIZE)) { + ret = doc_ecc_bch_fix_data(docg3, buf, hwecc); + if (ret < 0) { + mtd->ecc_stats.failed++; + ret = -EBADMSG; + } + if (ret > 0) { + mtd->ecc_stats.corrected += ret; + ret = -EUCLEAN; + } } doc_read_page_finish(docg3); @@ -849,7 +913,7 @@ static int doc_read_oob(struct mtd_info *mtd, loff_t from, from += DOC_LAYOUT_PAGE_SIZE; } - return 0; + return ret; err_in_read: doc_read_page_finish(docg3); err: @@ -1158,7 +1222,7 @@ static int doc_write_page(struct docg3 *docg3, loff_t to, const u_char *buf, if (ret) goto err; - doc_write_page_ecc_init(docg3, DOC_ECC_BCH_COVERED_BYTES); + doc_write_page_ecc_init(docg3, DOC_ECC_BCH_TOTAL_BYTES); doc_delay(docg3, 2); doc_write_page_putbytes(docg3, DOC_LAYOUT_PAGE_SIZE, buf); @@ -1721,7 +1785,11 @@ static int __init docg3_probe(struct platform_device *pdev) docg3_floors = kzalloc(sizeof(*docg3_floors) * DOC_MAX_NBFLOORS, GFP_KERNEL); if (!docg3_floors) - goto nomem; + goto nomem1; + docg3_bch = init_bch(DOC_ECC_BCH_M, DOC_ECC_BCH_T, + DOC_ECC_BCH_PRIMPOLY); + if (!docg3_bch) + goto nomem2; ret = 0; for (floor = 0; floor < DOC_MAX_NBFLOORS; floor++) { @@ -1751,10 +1819,13 @@ notfound: ret = -ENODEV; dev_info(dev, "No supported DiskOnChip found\n"); err_probe: + free_bch(docg3_bch); for (floor = 0; floor < DOC_MAX_NBFLOORS; floor++) if (docg3_floors[floor]) doc_release_device(docg3_floors[floor]); -nomem: +nomem2: + kfree(docg3_floors); +nomem1: iounmap(base); noress: return ret; @@ -1779,6 +1850,7 @@ static int __exit docg3_release(struct platform_device *pdev) doc_release_device(docg3_floors[floor]); kfree(docg3_floors); + free_bch(docg3_bch); iounmap(base); return 0; } diff --git a/drivers/mtd/devices/docg3.h b/drivers/mtd/devices/docg3.h index 397e461..33db727 100644 --- a/drivers/mtd/devices/docg3.h +++ b/drivers/mtd/devices/docg3.h @@ -51,10 +51,19 @@ #define DOC_LAYOUT_WEAR_OFFSET (DOC_LAYOUT_PAGE_OOB_SIZE * 2) #define DOC_LAYOUT_BLOCK_SIZE \ (DOC_LAYOUT_PAGES_PER_BLOCK * DOC_LAYOUT_PAGE_SIZE) + +/* + * ECC related constants + */ +#define DOC_ECC_BCH_M 14 +#define DOC_ECC_BCH_T 4 +#define DOC_ECC_BCH_PRIMPOLY 0x4443 #define DOC_ECC_BCH_SIZE 7 #define DOC_ECC_BCH_COVERED_BYTES \ (DOC_LAYOUT_PAGE_SIZE + DOC_LAYOUT_OOB_PAGEINFO_SZ + \ - DOC_LAYOUT_OOB_HAMMING_SZ + DOC_LAYOUT_OOB_BCH_SZ) + DOC_LAYOUT_OOB_HAMMING_SZ) +#define DOC_ECC_BCH_TOTAL_BYTES \ + (DOC_ECC_BCH_COVERED_BYTES + DOC_LAYOUT_OOB_BCH_SZ) /* * Blocks distribution |
